Internal grinding machine



Jan. 17, 1939. H. H. 'ASBRIDGE 4 4 INTEHNAL GRINDING MACHINE File dMarch 21,1938 2 Sheets-Sheet 1 1939. H. H. Assam: 4 ,043

' INTERNAL GRINDING MACHINE Filed March 21, 1958 2 Sheets-Sheet 2Patented Jan. 17, 1939 UNITED STATES PATENT OFFIEIIE INTERNAL GRINDINGMACHINE Application March 21,

1938, Serial No. 197,269

In Great Britain April 1, 1937 3 Claims.

This invention relates to internal grinding machines of the type inwhich the hole being ground is gauged intermittently for the purpose ofcon.- trolling the grinding operation and stopping the same when thehole is of correct size.

The object of the present invention is to provide improved means forcontrolling the gauging operation and for retracting the grinding wheelradially from the work surface when the hole is ground to size.

The invention comprises the arrangement (in an internal grinding machinein which the workpiece is reciprocated over the grinding wheel) whereinthe gauge is normally held away from the work-piece until the grindingoperation is approaching completion when it is permitted to move intoand remain in a gauging position but prevented from coming into contactwith the grinding wheel, the gauge when it enters the- Workpiece causingmechanism to retract the grinding wheel radially from contact with theworkpiece.

The invention further comprises the provision of electrical meansoperated when the feed to the grinding wheel is approaching its maximumto allow the gauging means to move into and remain in the gaugingposition.

The invention further comprises the provision of electrical meansoperated when the gauge goes into the ground hole in the workpiece tocause the grinding wheel to retract radially from contact with theworkpiece.

Referring to the accompanying explanatory drawings:

Figure 1 is a part elevation and part sectional elevation of part of agrinding machine constructed and arranged in one convenient form inaccordance with this invention.

Figure 2 is a plan View of the work headstock.

Figure 3 is a cross sectional elevation on the line 33 of Figure 1.

Figure 4 is a plan of Figure 3, with the grinding headstock removed andwith certain parts in section.

The work headstock a. has the mandrel b for the workcarrier c journalledtherein. A workpiece is shown at d. The grinding wheel a is carried bythe shaft e journalled in the grinding head i.

The work gauge 9 which is to gauge the hole in the workpiece dis carriedby the spindle h secured to a crosshead 2' which has sleeves 1' to rideupon bars it upon the workhead. One sleeve 7' has an electric contact mthereon which cooperates with a contact n to close a circuit through asolenoid 0 to be hereinafter referred to. There is a spring at ppressing the slide 2' in one direction and a spring at q pressing upon aplunger 1' secured to or integral with the armature of a solenoidindicated at s.

The table it carrying the workhead is reciprocated with short strokeswhen the workpiece is in position to be ground by the grinding wheel e,by the spring loaded part 11. projecting from the frame 11 fulcrumed atw and oscillated by the connecting rod .12 from a suitable crank.

An arm 4 which can be adjusted in position by the screwed stud 5 ismounted upon the bed of the machine by a suitable bracket y 50 that itremains stationary as the table 2 reciprocates. It can move to the leftin Figure 2 as the workhead is withdrawn to move the workpiececompletely clear of the grinding wheel after the grinding operation iscompleted. During the normal reciprocations of the table if when thegrinding operation is in progress, the arm 4 prevents the slide 2'moving sufficiently forward to allow the gauge 9 to come into contactwith the grinding wheel e.

The table. f carrying the grinding head (see Figure 3) has a slide 6therein from which projects the lug 1 which bears upon the cam 8 splinedupon the shaft 9. The counterbalance weight Ill holds the lug 1 againstthe cam 8 and therefore as the cam is turned by its shaft 9 gives therequisite feed movements to the grinding wheel. The shaft 9 is turned bygearing in the box 2 and there is a hand wheel I! on the shaft, saidhand wheel having a earn [2 thereon (see Figure 1). When the cam 8 isapproaching the position which gives the desired maximum amount of feedto the grinding wheel, the cam I2 thereon engages the member i3 andcloses the contacts l4, IS, with the result that a circuit whichincludes the solenoids s is closed and the solenoid energized. Theplunger 1' is then withdrawn and the slide i can come against the stop4, so permitting the gauge 9 to remain in its extreme right handposition whilst the workhead is reciprocated and the workpiece (I movedback and forth on to and off the gauge, if the gauge can enter the holein the workpiece. When the slide i is permitted to move to the right inFigure l, and the gauge can enter the workpiece, the contacts m, n closeand the solenoid o is energized. This results in the armature It? beingmoved to the left in Figure 4 and turning the lever I! about its fulcrum[8. The part is of the lever H which comes between the collars 28 on therod 2| coupled to the slide 6 then causes such slide to be moved in thedirection of the arrow 22 in Figure 4. The slot 23 in the table I inwhich the slide 6 moves is at an angle to the direction of movement ofthe table and movement of the slide in the direction of the arrow 22,causes the lug 1 to slide down the incline of the cam 8 under thepressure of the weight l9, so retracting the grinding wheel radiallyfrom the face of the workpiece. It will be understood that this occurswhen the workpiece is ground to size and the gauge Q can enter therein.

The operation of the mechanism is as follows:

During the normal grinding operation, the workhead is reciprocated bythe mechanism u, v, w, :r and the workpiece is carried with it. Thegauge 9 also reciprocates with the head, the stop 4 preventing anymovement which might cause the gauge to make contact with the grindingwheel 6. When the feed movement of the grinding wheel is approachingcompletion by the turning of the cam 8, contacts I and 15 are closed bythe cam l2 on the hand wheel II and the solenoid s is energized towithdraw the plunger r from the slide 2'. The latter now bear againstthe stop 4 under the pressure of the spring n so that at eachreciprocation of the workhead, the workpiece will be brought against thegauge 9. If the gauge can enter the ground hole in the workpiece, thecontact m will move against the contact 12 and the solenoid 0 will beenergized which will result in the slide 6 being moved and the grindingwheel quickly retracted radially from contact with the workpiece.

The feed control mechanism is similar to that described in my priorpatent specification No. 2,005,332, which also describes the means forreciprocating the worktable.

What I claim is:

1. In an internal grinding machine of the type specified, a grindinghead, a workhead, with means for its reciprocation, a workholder upon amandrel journaled in the workhead, a gauge supported in the workholderadjacent the workpiece, a rod extending through the mandrel supportingthe gauge, a slide mounted upon said rod, an adjustable non-moving partlimiting the movement of the slide towards the grinding head, a springpressing the slide towards the said nonmoving part, a solenoidcontrolled spring loaded part pressing the slide in the oppositedirection, an electric contact on the slide and,a co-operating contacton the slide support, feed mechanism for the grinding wheel head, meansupon said mechanism for closing the circuit through said solenoid whenthe feed movement is approaching completion, and solenoid operated meansfor moving the grinding head to retract the grinding wheel radially fromcontact with the workpiece when the contacts upon the slide and theslide support engage.

2. In an internal grinding machine as claimed in claim 1, a rotary cam.for feeding the grinding wheel head towards the surface being ground, aslide movable in the grinding head table having a lug thereon engagingsaid cam, a weight holding the lug against the cam, and a solenoid formoving said slide in said slot to vary the position of the lug upon thecam to retract the grinding wheel radially from contact with theworkpiece.

3. An internal grinding machine comprising a revoluble grinding wheel, arevoluble workpiece holder, means to produce relative movement betweensaid workpiece holder and grinding wheel to bring a workpiece in thesaid holder over said grinding wheel, means thereafter to impart shortaxial vibratory movements to said workpiece holder, a gauge mounted insaid workpiece holder, a spring constraining said gauge to movecoaxially with and towards the workpiece, mechanical means to preventsaid gauge entering the bore of the workpiece during movement ofvibration of the workpiece holder towards said grinding wheel,electrically controlled means to prevent said gauge entering the bore ofthe workpiece during movement of vibration of the workpiece away fromsaid grinding wheel and a switch arranged for actuation when grinding isnearly completed to put said electrical means out of action.

HARRY HALES ASBRIDGE.

